They actually started im tje late 30s and Ray wanted ro reduce costs to achieve speed at any given length.Lawleys then; later Graves. The 225 came first and 110 scaled down. Very few of the former were built. They easily beat 6 metres almost every time.They were not designed for a DIY builder.
Been a while since I read about the history of the class, but I'm believe the design was commissioned by Lawley's. The idea was to have a small one-design class that they could build on speculation to fill gaps in their production schedule and keep their staff employed between larger jobs. Why plywood? It was partly because it was a new material in 1946 and Lawley's wanted to experiment with it, and partly because the plywood design allowed Lawley's to make extensive use of gigs and templates.